Brazilian Study Shows That Cannabinoids Exhibit Anti-Inflammatory And Protective Effects On SARS-CoV-2-Infected Human Heart Cells

A new study by scientists from multi-institutions in Brazil has demonstrated that cannabinoid receptor agonists exhibit anti-inflammatory and protective effects on SARS-CoV-2-infected human heart cells.


 
Among the extrapulmonary manifestations of COVID-19 is myocardial injury, caused both directly and indirectly by SARS-CoV-2, and which is associated with a high risk of mortality. One of the hallmarks of severe COVID-19 is the “cytokine storm”, at which point the immune system malfunctions, leading to possible organ failure and death.
 
Cannabinoids are known to have anti-inflammatory properties by negatively modulating the release of pro-inflammatory cytokines.
 
In this study the researchers investigated the effects of the cannabinoid agonist WIN 55,212-2 (WIN) on SARS-CoV-2-infected human iPSC-derived cardiomyocytes (hiPSC-CMs). Although WIN did not modulate angiotensin-converting enzyme II, nor reduced SARS-CoV-2 infection and replication in hiPSC-CMs at the conditions tested, it had anti-inflammatory and protective effects by reducing the levels of interleukins 6, 8,18 and tumor necrosis factor-alpha (TNF-α) and lactate dehydrogenase (LDH) activity in these cells without causing hypertrophic cardiac damage. These findings suggest that cannabinoids should be further investigated as an alternative therapeutic tool for the treatment of COVID-19.
 
The study findings were published on a preprint server and are currently being peer reviewed.
 
While medical researchers continue to search for effective antidotes to treat direct and indirect damage caused by the SARS-CoV-2 coronavirus, the new study findings demonstrate the potential of cannabinoid receptor agonists to alleviate myocardial damage in this condition even in the absence of any inhibitory effect on viral infection as such.
 
Although the SARS-CoV-2 virus appears to be a primarily respiratory virus, it also brings about many other effects such as neurological signs and symptoms, gut symptoms, and cardiovascular features.
The SARS-CoV-2 coronavirus  uses the host cell membrane angiotensin-converting enzyme 2 (ACE2) as its entry receptor. ACE2 is expressed at high levels on cardiac muscle cells in patients who already have cardiovascular disease. Moreover, the virus was found to infect cardiomyocytes derived from induced pluripotent stem cells (iPSCs), called hiPSC-CMs.
 
Numerous studies have shown diffuse myocardial damage and inflammation with infiltration by immune cells. Moreover, hiPSC-CMs show a higher expression of inflammatory genes such as IL-6, IL-8, and TNF-α. https://stemcellres.biomedcentral.com/articles/10.1186/s13287-020-02033-7
 
https://www.jstage.jst.go.jp/article/circj/84/11/84_CJ-20-0881/_article
 
Importantly the resulting flood of inflammatory cytokines leads to changes in the heart muscle cells, such as arrhythmias, hypertrophy, cell death, and the transformation of fibroblasts into myofibroblasts.
 
Typical signs of cardiac muscle injury include high levels of creatine kinase and la ctate dehydrogenase activity (LDH).
 
This study focuses on a phytochemicals that can modulate these harmful effects in infected patients and help treat patients with severe COVID-19, including cardiovascular damage.
 
A key source of these phytochemicals is the cannabis plant (Cannabis sativa).It yields a number of pharmacological compounds such as phytocannabinoids, including delta-9-Tetrahydrocannabinol (THC), a highly psychoactive agent. Endocannabinoids and synthetic cannabinoids are also of great interest.
 
The cannabinoids included in this study are WIN 55,212–2 (WIN), a mixed CB1/CB2 agonist, is a compound with reported inhibitory effects on the expression of the HIV-1 virus in vitro. Cannabinoids have also been found to act on cannabinoid receptors type 1 (CB1R) and/or type 2 (CB2R) to reduce ACE2 expression in a range of epithelia in vitro and also have anti-inflammatory properties.
 
In past research, WIN was found to reduce microglial activation following lipopolysaccharide (LPS) exposure, decrease the levels of TNF-α and IL-6 in plasma, and reduce inflammation in lung epithelial cells treated with TNF-α, while enhancing inflammatory activity in macrophages. High levels of cannabinoids prevented inflammation in epithelia incubated with TNF-α and IFN-γ.
 
The study team however found that WIN does not affect the expression of ACE2 on hiPSC-CMs that express CB1R. Neither does this molecule prevent or reduce SARS-CoV infection by any ACE2-independent mechanism. WIN did not lead to a significant reduction in SARS-CoV-2 replication either.
 
To date, severe COVID-19 is thought to result from dysregulated inflammatory immune responses leading to excessive levels of inflammatory cytokines in the systemic circulation, leading to multi-organ damage. As such, the study found that WIN prevented high levels of cytokine release in infected cells exposed to WIN, relative to either controls or infected cells.
 
It has been found that the SARS-CoV-2 infection leads to apoptosis in hiPSC-CMs, leading to plasma membrane damage and the leakage of LDH. Thus, high levels of this molecule act as an injury marker. However, treatment with WIN is found to reduce LDH levels in SARS-CoV-2 infected cells compared to non-treated infected cells, though not to baseline levels.
 
The team explored the potential for cannabinoids to prevent and treat COVID-19 by virtue of their known anti-inflammatory, cell-protective and antiviral properties.
 
The study findings show that the synthetic cannabinoid WIN reduces cell damage following infection by SARS-CoV-2 in hiPSC-CMs.WIN also reduced cytokine release, already low, from cardiomyocytes infected with this virus.
 
Corresponding author Dr Stevens Rehena from the D’Or Institute for Research and Education (IDOR), Rio de Janeiro-Brazil told Thailand Medical News, “This is the first study showing anti-inflammatory and protective properties of a cannabinoid agonist in hiPSC-CMs infected with SARS-CoV-2.”
 
The study team suggested that the failure to downregulate ACE2 levels in infected hiPSC-CMs could be due to the protective role of ACE2 on cardiovascular health. The extensively expressed CB1 receptor failed to show any association with reduced infection or viral titer after WIN binding in hiPSC-CMs.
 
However the absence of CB2 expression on hiPSC-CMs may explain why WIN could not modulate SARS-CoV-2 infection or replication in these cells.
 
It was found that when exposed to stress, cardiac immune cells and fibroblasts are the chief cells engaged in producing inflammatory cytokines, but cardiac muscle cells also play a role. This study confirmed that hiPSC-CMs released IL-6, IL-8, and TNF-α at higher levels following SARS-CoV-2 infection.
 
The study team suggested that this could be due to the lack of oxygen due to the respiratory depression caused by lung damage in COVID-19 and uncontrolled systemic inflammation. As shown in earlier research involving Trypanosoma cruzi infection of heart muscle, local inflammatory cytokine release could also contribute.
 
Importantly WIN was associated with lower levels of all three cytokines released from infected hiPSC-CMs, supporting similar findings in other tissues exposed to toxic proteins. Thus, WIN appears to have anti-inflammatory and protective properties on cardiac cells infected with the virus.
 
Although other receptors such as TRP (transient receptor potential channel) family may be involved in WIN’s reduction of LDH levels, the high affinity for CB1 receptors shown by WIN indicates that these receptors are primarily involved in LDH activity reduction.
 
Significantly TRP modulation by WIN is observed only with high WIN levels, at tenfold the concentration used in the current study, which supports the role of CB1 receptors rather than TRP in modulating LDH activity.
 
The study findings support the anti-inflammatory and protective effect of cannabinoids, mediated by the CB1 receptor. This in vitro cardiac myocyte model should be followed up with more advanced studies to explore the potential clinical applications of cannabinoids in preventing heart muscle damage in SARS-CoV-2.
 
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